Explain why water molecules form on average two hydrogen bonds per molecule, whereas ammonia molecules (NH3) form only one.

A hydrogen bond requires both a lone pair of electrons on a O, N or F atom and a hydrogen atom. In water there are two lone pairs and two hydrogen atoms, allowing the formation of two hydrogen bonds. In ammonia, although there are three hydrogen atoms, there is only one lone pair of electrons on the N, and this means that only one hydrogen bond can form per molecule.

Related Chemistry A Level answers

All answers ▸

How does the anticancer agent cisplatin work?


In terms of bonding, state the order of boiling point of propane, ethanol and ethanal and why.


Name the type of reaction and outline the mechanism for the reaction of the alcohol (CH3)2CHOH with the acyl chloride CH3COCl. Explain which orbitals take part in the reaction.


What's added to Ethanoyl Chloride to make Methyl Ethanoate? Draw out the mechanism for this reaction. Why is this preferred to esterification?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences